NAEP Technical DocumentationSubstitute Public Schools for the 2008 Long-Term Trend (LTT) Assessment

Substitute schools were preselected for the public school samples by sorting the public school frame file according to the actual order used in the sampling process (the implicit stratification). Each sampled school had each of its nearest neighbors within the same sampling stratum on the school frame file identified as a potential substitute. The nearest neighbor with the closest estimated age-specific enrollment was chosen. This was done in order to facilitate the selection of about the same number of students within the substitute as would have been selected from the original sampled school. If both nearest neighbors were equally distant from the sampled school in their age-specific enrollment (an uncommon occurrence), one of the two was randomly selected.

Prior to identifying the nearest neighbors, schools were disqualified as potential substitutes if they were from a different PSU or state, or offered different grade levels. Schools were also disqualified as potential substitutes if they were already selected in the public school samples for long-term trend, field test, arts, or science interactive computer testing (ICT) or assigned as a substitute for another public school (earlier in the sort ordering). Schools assigned as substitutes for schools with age 17 students were disqualified as potential substitutes for schools with age 9 and age 13 students, and schools assigned as substitutes for schools with age 13 students were disqualified as potential substitutes schools with age 9 students.

There were 1, 3, and 6 substitute private schools used for the age 9, 13, and 17 components respectively.

Last updated 02 February 2011 (EH)

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